Feinting telegraph system



Jan 12, 1937. A. w. BREYFOGEL PRINTING TELEGRAPH SYSTEM Original Filed Dec. 30, 1930 M. v m h' Q N o R sana/)nappy NRI.

Reissued Jan. l2, 1937 UNITED STATES PATENT OFFICE 20,236 PRINTING 'rELaGaArn srs'rEM York Original No. 1,928,478, dated September 26, 1933,

Serial No. 505,609, December 30, 1930.

newed December 3, 1932. Application for reissue December 31, 1935, Serial No. 57,054

19 claims. (ci. 17a-52) This invention relates to a printing telegraph system, and in particular to a telegraph system in which thyratron or other grid-controlled, gasiled thermionic tubes are employed as relays for operating the magnets of telegraph printers in accordance with incoming signals. i"

An object of my invention is to devise a gridcontrolled, gas-iilled tube system' for telegraph printers in which there are no stabilizing batteries, andl in which the necessary operating potentials are supplied directly from potential drops across resistances connected in the plate circuit of the amplifier controlling these grid-controlled, gas-lled tubes.

Another object o! my invention ls to devise such a relay circuit in which the grid elements of the tubes are maintained at deiinite potentials with respect to the cathode elements at all times and are never left free or floating.

A further object of my invention is to devise a grid-controlled, gas-filled tube circuit for the operation oi' one or more telegraph printers in which upon the receipt of successive positive signal impulses the magnets of two printers are operated alternately, and during no signal impulse periods the magnets of only one printer are operated depending upon which printer was last operated by positive impulses, and negative signal impulses are ineifective to operate either printer.

This invention is an improvement upon the relay circuit disclosed in Figure 2 of the copending application of H. H. Haglund, SerialNo. 343,109, patented March 1i., 1933, No. 1,901,296.

My invention is illustrated in the accompanying drawing in which:

Figure 1 is a circuit diagram of the novel relay circuit of this invention; and r Figure 2 is a curve representing current variations in the `plate circuit of the amplifier controlling the thyratron relays. v

Referring to Figure 1, the general arrangement of the invention comprises a vacuum tube relay VT1 having its input connected to an incoming line L, and its output circuit controlling the input circuits of two relays T1 and Ta. Relay T1 controls the printer magnets of printer A through circuits completed by brushes BB1 asso- 'ciated with pick-up rings R1 and Ra, and by brushes BR: associated with plate rings Rs and R4. Relay Ta controls the magnets of printer B" through circuits completed by brushes BR1 associated with pick-up rings R1 and Rz, and by brushes BR: associated with plate rings Rs and Re.

The relay circuit may be describedl in more detail as follows: f

In the power or output stage of the vacuum tube amplier VT1 is a netw rk of resistances r1, n, ra, n, rs and n. These r istances are proportioned so that r1 is equalv to n, rz to f5, and n to ra, thus forming a parallel circuit as shown. The point A of this resistance network is connected at point F to the cathodes of the two tubes T1 and T2 through a resistance n. Point B is connected to the (a) segments of pick-up ring Rz and point D is connected to the (b) segments of pick-up ring R2. Point C is connected to the grid G1 of tube T1 and to the (a) segments oi' pick-up ring R1. Point E is connected to the grid Ga o1 tube Tn and toA` the (b) segments oi' pick-up ring R1. The plate P1 of tube T1 is connected to the solid plate ring Ra and the plate Pa of tube T: is connected to the solid plate ring R5. 'I'he segments of plate rings R4 and Re are connected through the selecting magnets of the A" and "B printers to plus battery Bz as shown. The negative side of the battery is connected to the point. A.

In order that the operation of the circuit may be made perfectly clear, it might be well to assume certain resistance and circuit values in some of the circuits. Assume the resistances r1, rz, r4 and rs to be 200 ohms each, ra and n to be 2000 ohms each and n equal to.7.5 ohms. Let -it further be assumed that for a given anode potential the thyratron tubes T1 and T2 will not start when the voltage on the grid is minus 4.5 volts or more with respect to the cathode but that they will start when the voltage on the grid is minus 4 volts or less with respect to the cathode. This voltage is very will deiined for thyratron tubes with a given anode potential. y

Let it also be assumed that the current in the power or output stage of the vacuum tube amplier VT1, varies between 25 and 55 milliamperes as shown in Fig. 2.

As is well known to engineers the polarity of 'the impulses is reversed by each stage of the amvpliiier (see Patent No. 1,347,049), or, as stated by H. J. Van der Bijl on page 259 of his book entitled, 'rnermiomc vacuum Tube," pubushed by McGraw-Hill Book Company, New York, The space currents in successive tubes are therefore 180 out of phase. Thus, in a four-stage amplifier, if the polarity. of the signal impressed upon the grid of the rst stage oi' the amplier is positive, the signal impressed upon the grid of the second stage will be negative, the signal impressed upon the grid oi the third stage will be positive and the signal impressed upon the grid ci the fourth stage will be negative.

Accordingly, in the present case it is assumed that the polarity of the signal impressed upon the grid of the fourth or output stage of the amplier is negative when the polarity of the received signal is positive and vice versa. Hence, in the assumed arrangement, when the polarity of the incoming signal is plus, the current is 25 milliamperes; when the signal is zero, the current is 40 milliamperes; and when the signal is minus the current is 55 milliamperes.

Suppose the polarity of the incoming signal is plus and the current in the plate circuit of the vacuum tube amplier is 25 milliamperes. This current will divide equally between the two branches oi the resistance network, 12.5 milliamperes flowing through the resistances r1, rs and n. These currentsproduce a potential drop of 2.5 volts across each of the resistances 1'1 and rz and r1 and rs. The potential at the point A will be plus 2.5 volts with respect to the potential at the points B and D and plus 5 volts with respect to the potential t the points C and E. Also the potential at the grids of the two tubes T1 and T: is minus 5 volts with respect to the point A and the cathodes since the grids of the two tubes T1 and T2 are connected respectively to the points C and E. This voltage is suil'lciently high to prevent either of the tubes T1 and T1 from starting according to the previous suppositions. The pickup brushes BR1 now make contact with the lal segments of rings R1 and Rz, and the plate brushes BR: make contact with the la segments of rings Ra and R4. Plus battery is placed on the plate P1 of tube T1 through ring R1, brushes BR1, segment la of ring R4, and No. 1 selecting magnet of the A printer. The brushes BR1 momentarily short-circuit the resistance fa thus causing the potential at the grid G1 of tube T1 to be reduced from 5 to 3.5 volts and tube T1 starts. Now 200 milliamperes of current flows from plus battery through No. 1 selecting magnet of the A" printer, through segment 1a of ring R4. brushes BR1, ring Ra, through plate P1 to cathodeof tube T1, through resistance R1 to minus battery. No. 1 selecting magnet of the A printer is operated. and the 200 milliamperes ilowing in this circuit produces a voltage drop of 1.5 volts across the resistance r1. This voltage drop is in the same direction as the voltage drop across the resistance r1 and,A raises the voltage at the point B to minus 4 volts with respect to the cathode.

'I'he pick-up brushes BR1 now pass onto the 1s segments of rings R1 and R1, and the brushes BR: pass onto the 111 segments of ring Rs. The brushes BR1 short-circuit the resistance rs causing the voltage at the grid Gz of tube T1 to fall from 6.5 volts to -4 volts and tube T1 starts. Current will now now from plus battery through No. 1 selecting magnet of the B" printer, through segment 1b of ring Re, brushes BR1, ring R5, through the plate P1 to cathode of tube T1, through resistance n to minus battery. No. 1 selecting magnet of the B" printer will be operated. and 400 milliamperes will iiow through the resistance n,

producing a voltage drop oi' 3 volts, which adds to the voltage drop across resistance r4 and raises the voltage at the point D to minus 5.5 volts. But, as tube T1 has already been started, it cannot be again influenced by the grid until the arc has been stopped by removing the anode potential. Tube T1 then continues to pass current.

'I'he plate brushes BR: now pass oiT the segment 1a of ring R4, removing the anode potential from the plate P1 of tube T1, thus causing the arc to stop and tube T1 ceases to function. This reduces the current through resistance r1 to 200 milliamperes and reduces the voltage drop across this resistance n to 1.5 volts. As the brushes BR1 now pass onto the 2a segments oi' rings R1 and Rz, and the brushes BR1 pass onto the 2a segments of rings R3 and R4, the resistancer: is again short-circuited and the voltage at the grid G1 of tube T1 is reduced from `6.5 volts to -4 volts and tube T1 again starts.

This cycle oi events will continue so long as the incoming signal is plus and the plate cur.- rent of the vacuum tube VT1 is 2 5 milliamperes, i. e. each tube T1 and T1 will start when the pickup brushes BR1 come in contact with the corresponding pick-up segments.

Suppose that the voltage of the incoming signal falls to zero as illustrated in Fig. 2 and that the current in the plate circuit oi the vacuum tube VT1 risesto 40 milliamperes. Also suppose that the tube Tz is operating and the brush BR: is still making contact with the plate segment 511.

When the pick-up brushes BR1 move onto the 1a segments of rings R1 and Rz, the resistance rz is again short-circuited but the voltage applied to the grid G1 of tube T1 is now minus 5.5 volts with respect to the cathode and tube T1 does not start. When the current in the plate circuit oi' the tube VT1 increased to 40 milliamperes, the drop across the resistance r1 increased from 2.5 to 4 volts and since tube T2 is still operating, the voltage drop oi.' 1.5 volts across the resistance r1 is aiding the voltage drop across the resistance r1 making the voltage on the grid G1 of tube T1 minus 5.5 volts with respect to the cathode. 'I'he brushes BR1 now -pass oil' the segment 5b of ring Re removing the anode potential from the plate Pz ot tube Ta, thus causing the arc to stop and tube T1 ceases to function. 'I'he voltage drop across the resistance n now falls to, zero. 'Ihe pick-up brushes BR1 now` move onto the ls segments ofrings R1 and Rauand the plate brushes BR: move onto the 1s segment of ring Re. The resistance rs is short-circuited by the brushes BR1 thus causing thevoltage at the grid Ga of tube Ta to fall from minus 8 to minus 4 volts, and tube T1 again starts.

This cycle of events will continue so long as the potential of the incoming signal remains zero and the plate current of the vacuum tube VT1 is 40 milliamperes. 'I'hat is, the relay tube which was last operated by a plus signal will alone continue to operate after the signal voltage has fallen to zero. 'I'he other tube will never operate so long as this condition continues.

Now suppose the incoming signal becomes minus and the current in the plate circuit of the vacuum tube VT1 rises to 55 milliamperes. This increase in current will produce an increased voltage drop across the reslstances r1, r1, r4 and rs. 'Ihe voltage drop across each of these resistances will be 5.5 volts. Also suppose that the tube T1 is operating and the brush BR: is still making contact with the plate segment 511.

When the pick-up brushes BR1 move onto the 1a segments oi' ringsRi and R1, the resistance rz is again short-circuited, and the voltage applied to the grid G1 of tube T1 becomes minus 'I volts with respect to the cathode, and tube T1 vcannot start. When the current in the plateV circuit of the tube VT1 increases to 55 milliamperes, the voltage drop across resistance r1 increased from 4 volts to 5.5 volts, and sine the tube Ta is still operating, the voltage drop of 1.5 volts across the resistance n is aiding the voltage drop across the resistance ri. making the voltage on the grid Gi of tube Ti minus '7 volts with respect to the cathode. The brushes BRa now pass ofi' the segment 5bremoving the anode potential from the plate Pz of tube T2 thus causing the are to stop, and tube T: ceases to function. The voltage drop across the resistance r1 now falls to zero. The pick-up brushes BRi now move onto the 1b segments of rings R1 and Rz and the plate brushes. move onto the 1b segment of ring Re. The resistance rs is short-circujted by the brushes BR1, this causing the voltage at the grid G2 of T2 to fallfrom minus 11 voltage to minus 5.5 volts. This voltage is above that necessary to permit the tube to start and tube T2 therefore, does not start. I

This cycle of events will continue so long as the incoming signal is minus in polarity and the plate current of the tube VTi is 55 milliamperes. That is, neither relay tube is operated when the incoming signal is minus.

From the foregoing it is seen that when the incoming signal is plus, each tube will start when the pick-up brushes BRi pass onto their associated pick-up segments, and when the incoming signal is minus, neither tube will start. Also, when the incoming signal falls to zero, one tube will start every time the pick-up segments associated with it are short-circuited by the pick-up brushes BRi. Which tube will start depends upon the position of the brushes and whether the incoming signal falls from plus to zero or rises from minus to zero.

From the foregoing description of the opera.- tion of the circuit, it will be seen that the grids of the two relay tubes never go plus, and that starting of the tubes is accomplished by reducing the negative bias to such a negative value as will perm'it starting. This makes the relay tubes more stable for the reason that if the grid goes positive, it` draws current and in doing so'builds up a charge which changes the grid potential needed to make the tube start.

It will also be noticed that all biasing or stabilizing batteries have been eliminated and that the grids of the relay tubes are kept at their proper potentials by the voltage drops in the signaling circuit itself. Furthermore, the grids of the two relay tubes are never disconnected from the signaling circuit and are never left free to be affected by extraneous pick-up or disturbances.

I claim:

1. In a signaling system, a signaling circuit, a grid-controlled, gas-nlled tube having its input circuit connected to said signaling circuit, means for normally maintaining the grid of said tube negative with respect to its cathode, and additional means responsive to positive signal impulses to reduce said negative biasing potential while maintaining its polarity the same.

2. In a signaling system, a signaling circuit, a grid-controlled, gas-lied tube having its input circuit connected to said signaling circuit, means for normally maintaining the grid of said tube negative with respect to its cathode, and additional means responsive to negative signal impulses to increase said negative potential.

3. In a signaling system, a signaling circuit, a grid-controlled, gas-filled tube having its input circuit connected to said signaling circuit, means for normally maintaining the grid of said tube negative with respect to its cathode, and means operable in synchronism with incoming signals for reducing said negative biasing potential during a positive signal period and during no-signal Iperiod while maintaining the biasing potential negative.

4. In a signaling system, a signaling circuit, a grid-controlled, gas-filled tube having its input circuit connected to said signaling circuit, means for normally maintaining the grid of said tube negative with respect tol its cathode, and means responsive to signal impulses to decrease said negative biasing potential for positive signals and increase said potential for negative signals while maintaining the polarity unchanged, and means operable in synchronism with said impulses for further reducing said negative biasing potential during positive and no signal periods.

5. In a signaling system, a signaling circuit including a resistance, a grid-controlled, gas-iilled tube having its input circuit connected across said resistance, means for establishing a direct current through said resistance to normally maintain the grid of said tube negative with respect to its cathode, and additional means for decreasing said biasing current upon the receipt of positive signals and increasing said biasing current upon receipt of negative signals.

6. In a signaling system, a signaling circuit including a resistance, a grid-controlled, gas-lled tube having its input circuit connected across said resistance, means for establishing a direct current through said resistance to normally maintain the grid of said tube negative with respect to its cathode, means for decreasing said biasing current upon the receipt of positive signals and increasing said biasing current upon receipt of negative signals, and means operable in synchronlsm with said signals for periodically reducing said negative biasing potential.

. 7. In a signaling system, a signaling circuit terminated with a vacuum tube amplifier, a source of current and a resistance in the output stage of said amplifier, a grid-controlled, gas-filled tube having its input circuit connected across at least a portion of said resistance whereby the Aplate current of said amplifier normally maintains the grid of said gas-filled tube negative with respect to its cathode, said vacuum tube amplifier being so connected to said signaling circuit that positive signals produce a decrease in the current through said resistance, and negative signals produce an increase in said current.

8. In a signaling system, a signaling circuit terminated with a vacuum tube amplifier, a source of current and a resistance in the output stage of said ampliier, a grid-controlled, gas-filled tube having its input circuit connected across at least a portion of said resistance whereby the plate current of said amplifier normally maintains the grid of said gas-filled tube negative with respect to its cathode, said vacuum tube amplifier being so connected to said signaling circuit that positive signals produce a decrease in the current through said resistance, and negative signals produce an increase in said current, and means operable in synchronism with incoming signals for periodically short-circuiting a portion of the resistance included in the input circuit of said gas-filled tube.

9. In a signaling system, a signaling circuit terminated with a vacuum tube amplifier having a divided output circuit, a resistance in each branch of said output circuit through which a portion of the plate current flows, a grid-conbranch of said output circuit and having its input circuit connected across 'at least a portion of said resistance, whereby the plate current of said amplliier normally maintains the grid of said gasillled tube negative with respect to its cathode. a pair of telegraph printers, one associated with each gas-illled tube, the plate circuit of each tube being completed through the selecting magnets of its corresponding printer through a pair of plate rings provided with a rotating brush, a pair of pick-up rings having a rotating brush operating in synchronism with the brushes o'i' said plate rings, and circuit connections between the resistance elements in said output circuit and said pick-up rings for alternately short-circuiting a portion of the resistance elements included in the input circuit of said gas-filled tubes in synchronism with incoming signals. l

10. In a signaling system, a signaling circuit, a gaseous conduction tube, means for converting signals of dierent polarities, received over said circuit, into signals of varying magnitude of current, means for producing discharges through said tube, selectively in accordance with the magnitude oi' said current, and current responsive means in the output circuit of said tube.

l1. In a signaling system, a source of telegraph'signals of varying magnitude of current, a gaseous conduction tube, means for producing discharges through said tube selectively, in accordance with the magnitude of said current and current responsive means in the output circuit of said tube.

12. In a telegraph system, a source of telegraph signals comprising positive, negative and zero selecting conditions, a gaseous. conduction tube and means responsive to said selecting conditions for controlling the operation of said tube, whereby discharges will be produced therein in accordance with said signal conditions.

13. In a telegraph system, a source of telegraph signals comprising positive, negative and zero selecting conditions, a gaseous conduction tube and means responsive to said selecting ccnditions for producing a discharge in said tube when signals of one polarity are received, for preventing a discharge from occurring therein when signals of the other polarity are-received, and for starting or preventing the occurrence oi' a discharge therein when signals of zero polarity are received, depending upon the preceding signal conditions.

14. In a telegraph system, a source of telegraph signals, a gaseous conduction tube having a control electrode, means for applying a potential to said controlelectrode in accordance with said telegraph signals and means for varying said applied potential during a predetermined portion of each signal impulse, whereby to control the starting of a discharge through said tube, and current control means in the output circuit of said tube.

15. In a telegraph system. a source of telegraph signals, a gaseous conduction tube having a control electrode, means for applying a potential to said control electrode in accordance with said telegraph signals and a distributor operating in synchronism with said signals for varying said applied potential-during a predetermined portion ofveach signal impulse, whereby to control the starting of a discharge through said tube, and current control means in the output circuit o! said tube.

16. In a telegraph system, a source of signal impulses, a pair of gaseous conduction tubes having starting electrodes, means for applying predetermined potentials to the starting electrodes of both of said tubes in accordance with every signal impulse received and local means for selectively varying the potential applied to one of said tubes, whereby said selective tube only responds to said signal impulse.

17. In a telegraph system, a source oi signal impulses, a pair of gaseous conduction tubes having starting electrodes, means for applying predetermined potentials to the starting electrodes of both of said tubesin accordance with every signal impulse received and local means operating in synchronism with said impulses for varying the potential applied to said tubes alternately, whereby said tubes respond alternately to said signal impulses. f

18. In a telegraph system, a source of signal impulses, a pair of gaseous conduction tubes having starting electrodes, means for applying predetermined potentials to the starting electrodes oi' both of said tubes in accordance with every signal impulse received, local means operating in synchronism with said impulses for varying l the potential applied to said tubes alternately,

whereby said tubes respond alternately to said signal impulses, and a separate recorder in the output circuit of each of said tubes.

19. In a telegraph system, a source of signals oi varying magnitudes, a resistance in circuit with said source oi' signals, a gaseous conduction ALBERT W. BREYFOGEL. 

